The present invention pertains to a closed circuit, variable speed transportation device offering all of the advantages of a funicular type system equipped with a kinematic chain.
Popular current transportation systems include a series of mobile components which are rigidly mounted with interconnection devices whose basic kinematics consist of a funicular system, and range from the early single cable tramways to the latest cable cars.
These systems were always impaired by a major disadvantage. The mobile component, that is, the seat, car, or the container, transported by the system whether it be designed for passenger or freight transportation, must necessarily be separated from its link, usually a chain or cable, which represents the kinematic element of the funicular system.
Therefore, upon entering the unloading or deceleration zones, the mobile component leaves a first programmed driving system, before being coupled with a second driving system programmed differently from the first one. For example, the mobile component leaves the cable representing the kinematic element of the funicular system, so as to be hooked to a slower cable, or to slow down by its own means. In terms of mechanics, this type of system is said to include a line kinematics and a stationary kinematics, different from the other one.
Recently, systems have been designed in which the mobile component remains rigidly mounted with the basic kinematic element, that of the funicular device, the latter being able to regulate the speed of the mobile component at the desired points. The mechanical principle of these systems consists of a chain whose link is of variable length and which is represented by a mobile component and a link. The variation of the length of the link provides the speed variation for the mobile component. However, such systems are also limited.
Such systems are limited by the fact that the tensile force applied to the link varies in inverse proportions to the speed. For example, if the speed varies from one unit to twenty units, the low speed tension applied to the link will be twenty times higher than the high speed tension. Therefore, it is necessary to proportion all of the components and the link with reference to low speed tensions, and, therefore, to use overdimensioned parts in high speed areas.
Such systems are further limited by the fact that, in a circuit looped on itself, the speed variation element should transmit the pulling effort to the total length of the circuit in the slow areas as well as in the high speed area.
Such systems are still further limited by the fact that the interconnection device, or tongs, of a mobile component on the chain, should be designed to pull a whole series of mobile components, so that its dimension is proportional to the length of the circuit and to the number of mobiles.
Aside from special applications, such as mountain type cable cars, the funicular type transportation systems could never be developed on a large scale since their disadvantages outweigh their advantages.
When the mobile component switches cable, many problems arise from the shaking motions, acceleration and jerking motions, as well as the lack of safety and reliability stemming from the repeated cable switching of the mobile component.
When a chain type system including links of various lengths is used, the funicular device is both a tractor and a speed regulator. In this case traffic and tension problems are encountered on the link, and drive, traction, and braking problems are also noted.